If you are using foobar2000 1.1 or newer, just use the built-in Install feature in the player. Open Preferences, which starts at the Components page the first time you use it after starting the player, then either click the Install button and locate the ZIP file, or drag the ZIP file onto the Preferences dialog.

If you are using an older version, just unpack the whole archive to the components folder, the db file should be in the same directory as the component.

I imagine this could offer several opportunities to improve the current AdLib plugin, for example complete support for A2M modules and its compressed version A2T. Adlib Tracker II's replay quality is more accurate compared to AdPlug, you may wan't to try the Winmap input plugin port provided by Danyl for comparison: In_Adt2 v0.96.2